diff --git a/sys/net/link_layer/net_if/net_if.c b/sys/net/link_layer/net_if/net_if.c
index 8314407c54..9eb26b60a7 100644
--- a/sys/net/link_layer/net_if/net_if.c
+++ b/sys/net/link_layer/net_if/net_if.c
@@ -142,7 +142,7 @@ int net_if_add_address(int if_id, net_if_addr_t *addr)
         return 0;
     }
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Address addition: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -166,7 +166,7 @@ int net_if_del_address(int if_id, net_if_addr_t *addr)
         return 0;
     }
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Address deletion: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -183,7 +183,7 @@ int net_if_del_address(int if_id, net_if_addr_t *addr)
 
 net_if_addr_t *net_if_iter_addresses(int if_id, net_if_addr_t **addr)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Address iteration: No interface initialized with ID %d.\n", if_id);
         return NULL;
     }
@@ -206,7 +206,7 @@ net_if_l3p_t net_if_get_l3p_types(int if_id)
 {
     net_if_l3p_t protocols;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Get L3 protocols: No interface initialized with ID %d.\n", if_id);
         return NET_IF_L3P_FAILURE;
     }
@@ -222,7 +222,7 @@ net_if_l3p_t net_if_get_l3p_types(int if_id)
 
 int net_if_add_l3p_types(int if_id, net_if_l3p_t protocols)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Add L3 protocols: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -236,7 +236,7 @@ int net_if_del_l3p_types(int if_id, net_if_l3p_t protocols)
 {
     net_if_addr_t *addr_ptr = NULL;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Remove L3 protocols: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -315,7 +315,7 @@ int net_if_send_packet(int if_id, uint16_t target, const void *payload,
           "payload_len = %d\n", if_id, target, payload, payload_len);
     uint32_t response;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Send packet: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
@@ -360,7 +360,7 @@ int net_if_send_packet_long(int if_id, net_if_eui64_t *target,
           payload_len);
     uint32_t response;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Send packet: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
@@ -398,7 +398,7 @@ int net_if_send_packet_long(int if_id, net_if_eui64_t *target,
 
 int net_if_register(int if_id, kernel_pid_t pid)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Register thread: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -410,7 +410,7 @@ int net_if_get_eui64(net_if_eui64_t *eui64, int if_id, int force_generation)
 {
     uint64_t tmp;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Get EUI-64: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -461,7 +461,7 @@ int net_if_set_eui64(int if_id, net_if_eui64_t *eui64)
 
     uint64_t tmp = NTOHLL(eui64->uint64);
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Set EUI-64: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -475,7 +475,7 @@ uint16_t net_if_get_hardware_address(int if_id)
 {
     uint16_t addr;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Get hardware address: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -486,7 +486,7 @@ uint16_t net_if_get_hardware_address(int if_id)
 
 uint16_t net_if_set_hardware_address(int if_id, uint16_t addr)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Set hardware address: No interface initialized with ID %d.\n", if_id);
         return 0;
     }
@@ -499,7 +499,7 @@ int32_t net_if_get_channel(int if_id)
 {
     int32_t channel;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Get channel: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
@@ -510,7 +510,7 @@ int32_t net_if_get_channel(int if_id)
 
 int32_t net_if_set_channel(int if_id, uint16_t channel)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Set channel: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
@@ -523,7 +523,7 @@ int32_t net_if_get_pan_id(int if_id)
 {
     int32_t pan_id;
 
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Get PAN ID: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
@@ -540,7 +540,7 @@ int32_t net_if_get_pan_id(int if_id)
 
 int32_t net_if_set_pan_id(int if_id, uint16_t pan_id)
 {
-    if (if_id < 0 || if_id > NET_IF_MAX || !interfaces[if_id].initialized) {
+    if (if_id < 0 || if_id >= NET_IF_MAX || !interfaces[if_id].initialized) {
         DEBUG("Set PAN ID: No interface initialized with ID %d.\n", if_id);
         return -1;
     }
diff --git a/sys/net/network_layer/sixlowpan/ip.c b/sys/net/network_layer/sixlowpan/ip.c
index 060b19462c..afb7920581 100644
--- a/sys/net/network_layer/sixlowpan/ip.c
+++ b/sys/net/network_layer/sixlowpan/ip.c
@@ -658,7 +658,9 @@ void ipv6_addr_init_prefix(ipv6_addr_t *out, const ipv6_addr_t *prefix,
     }
 
     memcpy(out, prefix, bytes);
-    out->uint8[bytes] = prefix->uint8[bytes] & mask;
+    if (bytes < 16) {
+        out->uint8[bytes] = prefix->uint8[bytes] & mask;
+    }
     memset(&(out[bytes + 1]), 0, 15 - bytes);
 }
 
diff --git a/sys/net/network_layer/sixlowpan/lowpan.c b/sys/net/network_layer/sixlowpan/lowpan.c
index 6e85a3514c..e79d5b1e25 100644
--- a/sys/net/network_layer/sixlowpan/lowpan.c
+++ b/sys/net/network_layer/sixlowpan/lowpan.c
@@ -486,6 +486,7 @@ lowpan_reas_buf_t *new_packet_buffer(uint16_t datagram_size,
             return new_buf;
         }
         else {
+            free(new_buf);
             return NULL;
         }
     }
@@ -1352,7 +1353,7 @@ void lowpan_iphc_decoding(uint8_t *data, uint8_t length, net_if_eui64_t *s_addr,
             case (0x03): {
                 /* 0-bits */
                 memcpy(&(ipv6_buf->srcaddr.uint8[0]), &ll_prefix[0], 2);
-                memset(&(ipv6_buf->srcaddr.uint8[2]), 0, 20);
+                memset(&(ipv6_buf->srcaddr.uint8[2]), 0, 6);
                 memcpy(&(ipv6_buf->srcaddr.uint8[8]), &s_addr->uint8[0], 8);
                 break;
             }
@@ -1561,9 +1562,10 @@ void lowpan_context_remove(uint8_t num)
 
     abr_remove_context(num);
 
-    for (j = i; j < NDP_6LOWPAN_CONTEXT_MAX; j++) {
+    for (j = i; j < (NDP_6LOWPAN_CONTEXT_MAX - 1); j++) {
         contexts[j] = contexts[j + 1];
     }
+    memset(&contexts[NDP_6LOWPAN_CONTEXT_MAX - 1], 0, sizeof(lowpan_context_t));
 }
 
 lowpan_context_t *lowpan_context_update(uint8_t num, const ipv6_addr_t *prefix,
diff --git a/sys/net/transport_layer/socket_base/socket.c b/sys/net/transport_layer/socket_base/socket.c
index cd826d0340..6d3cf2ceee 100644
--- a/sys/net/transport_layer/socket_base/socket.c
+++ b/sys/net/transport_layer/socket_base/socket.c
@@ -245,25 +245,25 @@ uint16_t socket_base_get_free_source_port(uint8_t protocol)
 
 int socket_base_socket(int domain, int type, int protocol)
 {
-    int i = 1;
+    int i = 0;
 
     while (socket_base_get_socket(i) != NULL) {
         i++;
     }
 
-    if (i > MAX_SOCKETS + 1) {
+    if (i > MAX_SOCKETS) {
         return -1;
     }
     else {
-        socket_t *current_socket = &socket_base_sockets[i - 1].socket_values;
-        socket_base_sockets[i - 1].socket_id = i;
+        socket_t *current_socket = &socket_base_sockets[i].socket_values;
+        socket_base_sockets[i].socket_id = i + 1;
         current_socket->domain = domain;
         current_socket->type = type;
         current_socket->protocol = protocol;
 #ifdef MODULE_TCP
         current_socket->tcp_control.state = 0;
 #endif
-        return socket_base_sockets[i - 1].socket_id;
+        return socket_base_sockets[i].socket_id;
     }
 }